McIlwee joins from the British Woodworking Federation where he has been chief executive officer since 2011.
He is also currently serving his second year as Vice Chairman of the Construction Products Association.
FIS President Andrew Smith said: `Iain really impressed our interview panel, and we were unanimous in our decision that he seemed an excellent fit to pick up the mantle from our previous chief executive David Frise, and drive FIS to new heights.
He is a clear and confident communicator, has a wealth of trade body experience, and a proven track record in building membership communities – exactly what we were looking for. The FIS Board, staff team and I very much look forward to working with him over the coming years.’
McIlwee added: ‘It is an exciting time to be joining FIS. The construction industry is changing and not before time.
“The impact of Grenfell echoes through the sector and we need to take note, ensure that the hard lessons are learned and never repeated.
“The collapse of Carillion is also leading us to look at the contractual nature of the construction process.
“As a sector we need to find better ways to collaborate to improve quality, safety and productivity, we need to balance on and off-site activity and truly embrace the digital revolution.”